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1.  Development of a genetic system for the deep-sea psychrophilic bacterium Pseudoalteromonas sp. SM9913 
Background
Pseudoalteromonas species are a group of marine gammaproteobacteria frequently found in deep-sea sediments, which may play important roles in deep-sea sediment ecosystem. Although genome sequence analysis of Pseudoalteromonas has revealed some specific features associated with adaptation to the extreme deep-sea environment, it is still difficult to study how Pseudoalteromonas adapt to the deep-sea environment due to the lack of a genetic manipulation system. The aim of this study is to develop a genetic system in the deep-sea sedimentary bacterium Pseudoalteromonas sp. SM9913, making it possible to perform gene mutation by homologous recombination.
Results
The sensitivity of Pseudoalteromonas sp. SM9913 to antibiotic was investigated and the erythromycin resistance gene was chosen as the selective marker. A shuttle vector pOriT-4Em was constructed and transferred into Pseudoalteromonas sp. SM9913 through intergeneric conjugation with an efficiency of 1.8 × 10-3, which is high enough to perform the gene knockout assay. A suicide vector pMT was constructed using pOriT-4Em as the bone vector and sacB gene as the counterselective marker. The epsT gene encoding the UDP-glucose lipid carrier transferase was selected as the target gene for inactivation by in-frame deletion. The epsT was in-frame deleted using a two-step integration–segregation strategy after transferring the suicide vector pMT into Pseudoalteromonas sp. SM9913. The ΔepsT mutant showed approximately 73% decrease in the yield of exopolysaccharides, indicating that epsT is an important gene involved in the EPS production of SM9913.
Conclusions
A conjugal transfer system was constructed in Pseudoalteromonas sp. SM9913 with a wide temperature range for selection and a high transfer efficiency, which will lay the foundation of genetic manipulation in this strain. The epsT gene of SM9913 was successfully deleted with no selective marker left in the chromosome of the host, which thus make it possible to knock out other genes in the same host. The construction of a gene knockout system for Pseudoalteromonas sp. SM9913 will contribute to the understanding of the molecular mechanism of how Pseudoalteromonas adapt to the deep-sea environment.
doi:10.1186/1475-2859-13-13
PMCID: PMC3930924  PMID: 24450434
2.  Prevalence and risk factors for depression and anxiety among outpatient migraineurs in mainland China 
The Journal of Headache and Pain  2012;13(4):303-310.
This study aimed to investigate the prevalence and risk factors for anxiety and depression symptoms in outpatient migraineurs in mainland China. In addition, we evaluated whether the Hospital Anxiety and Depression Scale (HADS) provided sufficient validity to screen depression and anxiety. A cross-sectional study was conducted consecutively at our headache clinic. Migraine was diagnosed according to International Classification of Headache Disorders, 2nd edition (ICHD-II). Demographic characteristics and clinical features were collected by headache questionnaire. Anxiety and depression symptoms about migraineurs were assessed using HADS. Several questionnaires were simultaneously used to evaluate patients with depressive disorder including the Hamilton Depression Rating Scale-17 (HAMD), Hamilton Anxiety Rating Scale (HAMA) and HADS. Pearson correlation analysis was applied to test the validity of HADS. 176 outpatients with migraine (81.8 % female) were included. Overall, 17.6 and 38.1 % participants had depression and anxiety, respectively. Possible risk factors for depression in migraineurs included headache intensity of first onset of migraine, migraine with presymptom, migraine with family history and migraine disability. The possible risk factors for anxiety included fixed attack time of headache in one day and poor sleeping, and age represented a protective factor for anxiety. The correlation coefficient of HADS-A and HADS-D with HAMA and HAMD was 0.666 and 0.508, respectively (P < 0.01). This study demonstrates that depression and anxiety comorbidity in our mainland Chinese migraineurs are also common, and several risk factors were identified that may provide predictive value. These findings can help clinicians to identify and treat anxiety and depression in order to improve migraine management.
doi:10.1007/s10194-012-0442-9
PMCID: PMC3356469  PMID: 22466285
Anxiety; Cross-sectional study; Depression; Migraine; Risk factor
3.  Classification and clinical features of headache patients: an outpatient clinic study from China 
The Journal of Headache and Pain  2011;12(5):561-567.
This study aimed to analyze and classify the clinical features of headache in neurological outpatients. A cross-sectional study was conducted consecutively from March to May 2010 for headache among general neurological outpatients attending the First Affiliated Hospital of Chongqing Medical University. Personal interviews were carried out and a questionnaire was used to collect medical records. Diagnosis of headache was according to the International classification of headache disorders, 2nd edition (ICHD-II). Headache patients accounted for 19.5% of the general neurology clinic outpatients. A total of 843 (50.1%) patients were defined as having primary headache, 454 (27%) secondary headache, and 386 (23%) headache not otherwise specified (headache NOS). For primary headache, 401 (23.8%) had migraine, 399 (23.7%) tension-type headache (TTH), 8 (0.5%) cluster headache and 35 (2.1%) other headache types. Overall, migraine patients suffered (1) more severe headache intensity, (2) longer than 6 years of headache history and (3) more common analgesic medications use than TTH ones (p < 0.001).TTH patients had more frequent episodes of headaches than migraine patients, and typically headache frequency exceeded 15 days/month (p < 0.001); 22.8% of primary headache patients were defined as chronic daily headache. Almost 20% of outpatient visits to the general neurology department were of headache patients, predominantly primary headache of migraine and TTH. In outpatient headaches, more attention should be given to headache intensity and duration of headache history for migraine patients, while more attention to headache frequency should be given for the TTH ones.
doi:10.1007/s10194-011-0360-2
PMCID: PMC3173628  PMID: 21744226
Outpatient; Headache; Cross-sectional study; Clinical feature; Migraine
4.  Classification and clinical features of headache patients: an outpatient clinic study from China 
The Journal of Headache and Pain  2011;12(5):561-567.
This study aimed to analyze and classify the clinical features of headache in neurological outpatients. A cross-sectional study was conducted consecutively from March to May 2010 for headache among general neurological outpatients attending the First Affiliated Hospital of Chongqing Medical University. Personal interviews were carried out and a questionnaire was used to collect medical records. Diagnosis of headache was according to the International classification of headache disorders, 2nd edition (ICHD-II). Headache patients accounted for 19.5% of the general neurology clinic outpatients. A total of 843 (50.1%) patients were defined as having primary headache, 454 (27%) secondary headache, and 386 (23%) headache not otherwise specified (headache NOS). For primary headache, 401 (23.8%) had migraine, 399 (23.7%) tension-type headache (TTH), 8 (0.5%) cluster headache and 35 (2.1%) other headache types. Overall, migraine patients suffered (1) more severe headache intensity, (2) longer than 6 years of headache history and (3) more common analgesic medications use than TTH ones (p < 0.001).TTH patients had more frequent episodes of headaches than migraine patients, and typically headache frequency exceeded 15 days/month (p < 0.001); 22.8% of primary headache patients were defined as chronic daily headache. Almost 20% of outpatient visits to the general neurology department were of headache patients, predominantly primary headache of migraine and TTH. In outpatient headaches, more attention should be given to headache intensity and duration of headache history for migraine patients, while more attention to headache frequency should be given for the TTH ones.
doi:10.1007/s10194-011-0360-2
PMCID: PMC3173628  PMID: 21744226
Outpatient; Headache; Cross-sectional study; Clinical feature; Migraine

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